Prenatal hypoxia is one of the most significant clinical challenges facing obstetrics today. Adverse in utero conditions that result in reduced oxygen delivery to the fetus generate fetal growth restriction associated with morbidity and mortality. Epidemiological and animal studies have convincingly shown that growth-restricted fetuses have an increased risk of adult cardiovascular disease. We have shown that prenatal hypoxia of pregnant guinea pigs generates a fetal cardiac phenotype of inflammation, oxidative and nitrosative stress, and altered mitochondrial enzyme activity. Further, the offspring exhibit reduced mitochondrial protein expression, mitochondrial respiration and cardiac performance. Mitochondria are important for energy production of the cardiac cell whose normal function is critical for cell survival. We hypothesize that intrauterine hypoxia permanently alters fetal cardic mitochondrial respiration via epigenetic mechanisms associated with DNA methylation, compromising heart function in the offspring. We will study the effects of prenatal hypoxia on 90d old guinea pig offspring and determine the programming effects on the 1) mitochondrial respiratory capacity, mRNA/protein expression, and DNA methylation of isolated cardiac cells of offspring hearts, 2) protective effects of prenatal treatment against nitrosative and oxidative stress on cardiac function of offspring hearts, and 3) the vulnerability of heart function to subsequent stressors via pressure overload and fatty acid excess. We will use state-of-the-art approaches for investigating epigenetic mechanisms (DNA methylation), mitochondrial respiration (Sea Horse Bioscience XF24 Analyzer) of freshly cardiac cells, and cardiac performance (non-invasive echocardiography) in guinea pig offspring exposed to normoxia and hypoxia in utero. Responses to subsequent physiological challenges such as aortic pressure overload and high fat diet will be measured to identify the translational impact of fetal hypoxemia on the vulnerability of offspring hearts to cardiac failure. This will bring a new perspective on te role of the mitochondrion as an important target site of oxidative damage in utero in contributing as a causative factor in cardiac dysfunction in the offspring.